The Setup is a mission during Chapter I.
The mission starts when Jimmy is being lectured by Dr. Crabblesnitch about Jimmy's fighting. Jimmy explains this is because of the amount of bullies the school has, with Dr. Crabblesnitch explaining that its just 'school spirit' and that when he was at school bullying the new kid was normal.
After Dr. Crabblesnitch leaves, Jimmy is confronted by Davis, who accuses Jimmy of being a teacher's pet. Jimmy denies this, but Davis attacks Jimmy with his slingshot which prompts Jimmy to chase him.
Davis runs away at full speed. If he gets too far ahead of Jimmy, the mission is failed.
Outside the Auto Repair Shop gates, he's attacked by Wade. The game instructs the player to shove Wade into a trashcan and provides a tutorial on how to do so, although Wade can just be fought as normal instead.
After dealing with Wade, Jimmy has to open the gates. He must then make his way through the buildings and parking lots of the shop, fending off Trent, Ethan, Tom, and Wade again (the other bully, Troy, is absent from the mission).
Davis takes refuge on a platform made of scrap wood and old barrels, kicking the ladder down so Jimmy can't use it.
Although he only takes a few hits to defeat, Davis has a large lifebar at the top of the screen, and for that reason can be considered a boss.
Davis fires at Jimmy with the slingshot. There isn't much strategy to avoiding it, although by keeping his distance and running Jimmy may avoid the shots. The closer he is, the more difficult to dodge. If Jimmy picks up a garbage can lid, he can use it to block the shots.
To win the fight, Jimmy has to knock Davis off the platform. The ground in front of them is littered with loose bricks and a few garbage can lids. These can be thrown at Davis. Alternately, if Jimmy has firecrackers in his inventory, he can throw them at Davis. After three hits with the brick and lids or two hits with the firecrackers, Davis' platform crumbles and he falls to the ground. Jimmy takes the slingshot for his own.